package nz.ac.massey.cs.misc.dependency_checker;

import java.util.HashSet;
import java.util.Set;
import org.objectweb.asm.AnnotationVisitor;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.FieldVisitor;
import org.objectweb.asm.Handle;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
import org.objectweb.asm.signature.SignatureReader;
import org.objectweb.asm.signature.SignatureVisitor;

public class DependencyCollector extends ClassVisitor {

	private Set<String> referenced = new HashSet<String>();

	public Set<String> getReferenced() {
		return referenced;
	}

	public DependencyCollector() {
		super(Opcodes.ASM4);
	}

	@Override
	public void visit(final int version, final int access, final String name,final String signature, final String superName,final String[] interfaces) {

		if (superName != null) {
			createDependency(superName);
		}
		if (interfaces != null) {
			for (String i : interfaces) {
				createDependency(i);
			}
		}
		if (signature != null) {
			SignatureVisitor v = new SignatureDependencyVisitor();
			SignatureReader r = new SignatureReader(signature);
			r.accept(v);
		}
	}

	@Override
	public AnnotationVisitor visitAnnotation(final String desc,final boolean visible) {
		addDesc(desc);
		return new AnnotationDependencyVisitor();
	}

	@Override
	public FieldVisitor visitField(final int access, final String name,final String desc, final String signature, final Object value) {

		if (signature == null) {
			addDesc(desc);
		} else {
			addTypeSignature(signature);
		}
		if (value instanceof Type) {
			addType((Type) value);
		}
		return new FieldDependencyVisitor();
	}

	@Override
	public MethodVisitor visitMethod(final int access, final String name,final String desc, final String signature, final String[] exceptions) {
		if (signature == null) {
			addMethodDesc(desc);
		} else {
			// this is a method signature, not a type signature
			addSignature(signature);
		}
		addInternalNames(exceptions);
		return new MethodDependencyVisitor();
	}

	class AnnotationDependencyVisitor extends AnnotationVisitor {

		public AnnotationDependencyVisitor() {
			super(Opcodes.ASM4);
		}

		@Override
		public void visit(final String name, final Object value) {
			if (value instanceof Type) {
				addType((Type) value);
			}
		}

		@Override
		public void visitEnum(final String name, final String desc,
				final String value) {
			addDesc(desc);
		}

		@Override
		public AnnotationVisitor visitAnnotation(final String name,
				final String desc) {
			addDesc(desc);
			return this;
		}

		@Override
		public AnnotationVisitor visitArray(final String name) {
			return this;
		}
	}

	class FieldDependencyVisitor extends FieldVisitor {

		public FieldDependencyVisitor() {
			super(Opcodes.ASM4);
		}

		@Override
		public AnnotationVisitor visitAnnotation(String desc, boolean visible) {
			addDesc(desc);
			return new AnnotationDependencyVisitor();
		}
	}

	class MethodDependencyVisitor extends MethodVisitor {

		public MethodDependencyVisitor() {
			super(Opcodes.ASM4);
		}

		@Override
		public AnnotationVisitor visitAnnotationDefault() {
			return new AnnotationDependencyVisitor();
		}

		@Override
		public AnnotationVisitor visitAnnotation(final String desc,
				final boolean visible) {
			addDesc(desc);
			return new AnnotationDependencyVisitor();
		}

		@Override
		public AnnotationVisitor visitParameterAnnotation(final int parameter,
				final String desc, final boolean visible) {
			addDesc(desc);
			return new AnnotationDependencyVisitor();
		}

		@Override
		public void visitTypeInsn(final int opcode, final String type) {
			addType(Type.getObjectType(type));
		}

		@Override
		public void visitFieldInsn(final int opcode, final String owner,
				final String name, final String desc) {
			addInternalName(owner);
		}

		@Override
		public void visitMethodInsn(final int opcode, final String owner,
				final String name, final String desc) {
			addInternalName(owner);
		}

		@Override
		public void visitInvokeDynamicInsn(String name, String desc,
				Handle bsm, Object... bsmArgs) {
			addMethodDesc(desc);
			addConstant(bsm);
			for (int i = 0; i < bsmArgs.length; i++) {
				addConstant(bsmArgs[i]);
			}
		}

		@Override
		public void visitLdcInsn(final Object cst) {
			addConstant(cst);
		}

		@Override
		public void visitMultiANewArrayInsn(final String desc, final int dims) {
			addDesc(desc);
		}

		@Override
		public void visitLocalVariable(final String name, final String desc,
				final String signature, final Label start, final Label end,
				final int index) {
			if (signature == null) {
				addDesc(desc);
			} else {
				addTypeSignature(signature);
			}
		}

		@Override
		public void visitTryCatchBlock(final Label start, final Label end,
				final Label handler, final String type) {
			if (type != null) {
				addInternalName(type);
			}
		}
	}

	class SignatureDependencyVisitor extends SignatureVisitor {

		String signatureClassName;

		public SignatureDependencyVisitor() {
			super(Opcodes.ASM4);
		}

		@Override
		public void visitClassType(final String name) {
			// System.out.println("visit class in signature: " + name);
			if (signatureClassName == null) {
				signatureClassName = name; // top level !
			}
			addInternalName(name);
		}

		@Override
		public void visitInnerClassType(final String name) {
			signatureClassName = signatureClassName + "$" + name;
			addInternalName(signatureClassName);
		}
	}

	private void addName(final String name) {
		createDependency(name);
	}

	void addInternalName(final String name) {
		addType(Type.getObjectType(name));
	}

	private void addInternalNames(final String[] names) {
		for (int i = 0; names != null && i < names.length; i++) {
			addInternalName(names[i]);
		}
	}

	void addDesc(final String desc) {
		addType(Type.getType(desc));
	}

	void addMethodDesc(final String desc) {
		addType(Type.getReturnType(desc));
		Type[] types = Type.getArgumentTypes(desc);
		for (int i = 0; i < types.length; i++) {
			addType(types[i]);
		}
	}

	void addType(final Type t) {
		switch (t.getSort()) {
		case Type.ARRAY:
			addType(t.getElementType());
			break;
		case Type.OBJECT:
			addName(t.getInternalName());
			break;
		case Type.METHOD:
			addMethodDesc(t.getDescriptor());
			break;
		}
	}

	private void addSignature(final String signature) {
		if (signature != null) {
			new SignatureReader(signature)
					.accept(new SignatureDependencyVisitor());
		}
	}

	void addTypeSignature(final String signature) {
		if (signature != null) {
			try {
				new SignatureReader(signature)
						.acceptType(new SignatureDependencyVisitor());
			} catch (Exception x) {
				System.err.println("Error visiting signature " + signature);
			}
		}
	}

	void addConstant(final Object cst) {
		if (cst instanceof Type) {
			addType((Type) cst);
		} else if (cst instanceof Handle) {
			Handle h = (Handle) cst;
			addInternalName(h.getOwner());
			addMethodDesc(h.getDesc());
		}
	}

	private String convertName(String name) {
		return name.replace('/', '.');
	}

	private void createDependency(String targetName) {
		String qname = convertName(targetName);
		referenced.add(qname);
	}

}
